Nonsurgical bleeding diathesis in anemic thrombocytopenic patients: role of temperature, red blood cells, platelets, and plasma-clotting proteins

Analysis of bleeding outcomes in patients with hypoproliferative thrombocytopenia in the A-TREAT clinical trial

BACKGROUND

Despite prophylactic platelet transfusions, hypoproliferative thrombocytopenia is associated with bleeding; historical risk factors include hematocrit (HCT)≤ $$ \le $$ 25%, activated partial thromboplastin time≥ $$ \ge $$ 30 s, international normalized ratio≥ $$ \ge $$ 1.2, and platelets≤ $$ \le $$ 5000/μL.

METHODS

We performed a post hoc analysis of bleeding outcomes and risk factors in participants with hematologic malignancy and hypoproliferative thrombocytopenia enrolled in the American Trial to Evaluate Tranexamic Acid Therapy in Thrombocytopenia (A-TREAT) and randomized to receive either tranexamic acid (TXA) or placebo.

RESULTS

World Health Organization (WHO) grade 2+ bleeding occurred in 46% of 330 participants, with no difference between the TXA (44%) and placebo (47%) groups (p = 0.66). Overall, the most common sites of bleeding were oronasal (18%), skin (17%), gastrointestinal (11%), and genitourinary (11%). Among participants of childbearing potential, 28% experienced vaginal bleeding. Platelets ≤5000/μL and HCT < 21% (after adjusting for severe thrombocytopenia) were independently associated with increased bleeding risk (HR 3.78, 95% CI 2.16-6.61; HR 2.67, 95% CI 1.35-5.27, respectively). Allogeneic stem cell transplant was associated with nonsignificant increased risk of bleeding versus chemotherapy alone (HR 1.34, 95% CI 0.94-1.91).

DISCUSSION

The overall rate of WHO grade 2+ bleeding was similar to previous reports, albeit with lower rates of gastrointestinal bleeding. Vaginal bleeding was common in participants of childbearing potential. Platelets ≤5000/μL remained a risk factor for bleeding. Regardless of platelet count, bleeding risk increased with HCT < 21%, suggesting a red blood cell transfusion threshold above 21% should be considered to mitigate bleeding. More investigation is needed on strategies to reduce bleeding in this population.

Perioperative Blood Transfusion in Head and Neck Cancer Revisited

OBJECTIVE

To reevaluate the frequency of perioperative blood transfusion, transfusion triggers, and survival impact in patients with incident, surgically treated head and neck cancer (HNC) in restrictive transfusion regimens.

METHODS

Retrospective analysis of surgically treated patients with incident HNC with and without perioperative blood transfusion between 2008 and 2019 at the Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Innsbruck, according to the department's clinical Head and Neck Tumor Registry.

RESULTS

Of the 590 patients included, perioperative transfusions were administered in 6.3% (n = 37, transfusion group). Following multivariable logistic regression, likelihood of blood transfusions was increased in patients with poorer general health conditions (ASA score III/IV; OR 3.7; 95% CI 1.9-8.6; p = 0.002), hemoglobin <12.5 g/dL (OR 2.7; 95% CI 1.1-6.4; p = 0.03), longer duration of surgery (OR 1.006 per minute of surgery time; 95% CI 1.003-1.008; p < 0.001), and negative p16 status (OR 5.3; 95% CI = 1.1-25; p = 0.03). Based on 14 matching variables related to survival and perioperative blood transfusion, a control group of 37 matching patients without perioperative transfusion was identified. Using univariate analysis, overall survival in transfusion and control groups did not differ significantly (p = 0.25). After adjusting for four parameters with limited matching accuracy (Chi square p < 0.2) in Cox regression analysis, a transfusion related hazard ratio close to 1 (HR 0.92; 95% CI 0.34-2.51; p = 0.87) was observed.

CONCLUSION

Considering current restrictive transfusion regimens and general transfusion risks, the administration of blood products in HNC patients during the perioperative period is not associated with additional oncologic hazard.

LEVEL OF EVIDENCE

III Laryngoscope, 2022.

Transfusion as a Palliative Strategy

PURPOSE OF REVIEW

The palliative care population is a complex and heterogeneous one. While transfusion therapy is a readily available intervention for many patients, inadequate knowledge for accurately identifying which patient subsets at end-of-life will benefit from a transfusion, along with an unclear understanding of the magnitude of attendant risks of transfusion in those receiving palliative care, complicates the risk-benefit assessment of this therapy. In this brief review, the current literature surrounding transfusion of red cells and platelets in the palliative care patient population will be reviewed and recommendations provided.

RECENT FINDINGS

Benefits of transfusion therapy include subjective relief of fatigue and dyspnea, and improved sense of wellness, amongst other findings. However, these responses are not durable and there are currently no validated, objective metrics that correlate with symptomatic improvements. It is clear that transfusion-associated adverse reactions are underestimated in those receiving palliative care, with reaction rates similar to the general patient population. Additionally, based on the high mortality rates reported soon after transfusion, the impact of these blood components must be considered as an exacerbating or causative factor of mortality when evaluating declining condition or death. Hematinics are rarely assessed in anemic palliative care patients or, when measured, are often not corrected. The decision to transfuse palliative care patients is multifactorial, and benefits, risks, patient wishes, blood component inventories, and alternatives to transfusion should all be considered. There are many unknowns regarding transfusion in palliative care. Critical next steps for optimizing blood component therapy in this population include high-quality trials that help to identify validated measures of objective functional changes that parallel patient-reported outcomes and subsets of patients receiving end-of-life care that will most likely be positively impacted by transfusion therapy.

Inability to Reverse Aspirin and Clopidogrel-induced Platelet Dysfunction with Platelet Infusion

Background Platelets are commonly administered to trauma patients to reverse the effects of pre-injury anti-platelet drugs if these individuals are judged to be at risk for ongoing bleeding (i.e., traumatic brain injury). In the U.S. blood banks, platelets are maintained at room temperature and are not infused prior to 72 hours storage due to rigorous screening methods. Recent work suggested that cold refrigerated platelets may be effective at restoring platelet function. We hypothesized that refrigerated platelets might be superior to room temperature platelets in reversing aspirin and clopidogrel-induced platelet dysfunction. Methods Using a cross-over design, 10 healthy, adult subjects underwent platelet removal by apheresis, received anti-platelet drugs (aspirin 325 mg and clopidogrel 75 mg) daily for three days, and then had return of their own platelets (about 3 x 10¹¹ platelets). Five subjects were randomly assigned to receive platelets stored at 4°C, and five received platelets stored at room temperature. One month later, this entire process was repeated with each subject receiving platelets stored by the alternative method. Thus, subjects served as their own controls. At multiple time points during the study in vivo platelet function was assessed by bleeding times, which were measured by a single observer blinded to patient group. Results Bleeding times rose dramatically after anti-platelet drugs were given, but remained well above the normal range (seven minutes) despite reinfusion of platelets. There were no differences in platelet function according to the method of storage. Conclusions Transfusion with autologous platelets appears to be ineffective in reversing the anti-platelet effects of aspirin and clopidogrel. Cold refrigerated platelets were no more effective than room temperature stored platelets in restoring platelet function. This abstract was presented at American College of Surgeons-clinical congress, Boston 10-22-2018. (Khoury L, Cohn S, Panzo M. Inability to Reverse Aspirin and Clopidogrel-Induced Platelet Dysfunction with Platelet Infusion. Journal of the American College of Surgeons. 2018. 227. S265. DOI: 10.1016/j.jamcollsurg.2018.07.546).

Preventing and managing catastrophic bleeding during extracorporeal circulation

The use of extracorporeal circulation for cardiac surgery and extracorporeal life support poses tremendous challenges to the hemostatic equilibrium given its diametric tendency to trigger hyper- and hypocoagulopathy. The necessity of anticoagulant therapy to counteract the hemostatic activation by the extracorporeal circuitry compounded by unfavorable patient and surgical factors significantly increase the risk of catastrophic bleeding in patients who require extracorporeal circulation. Preoperative measures, such as stratification of high-risk bleeding patients, and optimization of the modifiable variables, including anemia and thrombocytopenia, provide a crude estimation of the likelihood and may modify the risk of catastrophic bleeding. The anticipation for catastrophic bleeding subsequently prompts the appropriate preparation for potential resuscitation and massive transfusion. Equally important is intraoperative prevention with the prophylactic application of tranexamic acid, an antifibrinolytic agent that has promising benefits in reduction of blood loss and transfusion. In the event of uncontrolled catastrophic bleeding despite preemptive strategies, all effort must be centered on regaining hemostasis through surgical control and damage control resuscitation to protect against worsening coagulopathy and end organ failure. When control of bleeding is reinstated, management should shift focus from systemic therapy to targeted hemostatic therapy aimed at the potential culprits of coagulopathy as identified by point of care hemostatic testing. This review article outlines the strategies to appropriately intervene using prediction, prevention, preparation, protection, and promotion of hemostasis in managing catastrophic bleeding in extracorporeal circulation.

Are There Modifiable Risk Factors to Improve AKI?

Acute kidney injury (AKI) is a common critical syndrome, with high morbidity and mortality. Patients with AKI typically have an adverse prognosis, from incident chronic kidney disease (CKD), progression to end-stage renal disease (ESRD), subsequent cardiovascular disease, and ultimately death. However, there is currently no effective therapy for AKI. Early detection of risk factors for AKI may offer a good approach to prevention or early intervention. Traditional risk factors include extreme age, many common comorbid diseases, such as preexisting CKD, some specific exposures, such as sepsis, and exposure to some nephrotoxic agents. Recently, several novel risk factors for AKI, such as hyperuricemia, hypoalbuminemia, obesity, anemia, and hyperglycemia, have been identified. The underlying mechanisms between these nontraditional risk factors and AKI and whether their correction can reduce AKI occurrence remain to be clarified. This review describes the current epidemiology of AKI, summarizes its outcome, outlines the traditional risk profile, and finally highlights some recently identified novel risk factors.

Recovery from Cyclophosphamide Overdose in a Dog

An adult female spayed dog was evaluated after inadvertently receiving a total dose of 1,750 mg oral cyclophosphamide, equivalent to 2,303 mg/m2, over 21 days (days −21 to 0). Nine days after the last dose of cyclophosphamide (day +9), the dog was evaluated at Perth Veterinary Specialists. Physical examination revealed mucosal pallor, a grade 2/6 systolic heart murmur, and severe hemorrhagic cystitis. Severe nonregenerative pancytopenia was detected on hematology. Broad spectrum antibiotics, two fresh whole blood transfusions, granulocyte colony stimulating factor, and tranexamic acid were administered. Five days after presentation (day +14), the peripheral neutrophil count had recovered, and by 12 days (day +21) the complete blood count was near normal. A second episode of thrombocytopenia (day +51) was managed with vincristine, prednisolone, and melatonin. The dog made a complete recovery with no long-term complications at the time of writing. To the author's knowledge, this is the highest inadvertently administered dose of cyclophosphamide to result in complete recovery.

The Effect of Hematocrit on Platelet Adhesion: Experiments and Simulations

The volume fraction of red blood cells (RBCs) in a capillary affects the degree to which platelets are promoted to marginate to near a vessel wall and form blood clots. In this work we investigate the relationship between RBC hematocrit and platelet adhesion activity. We perform experiments flowing blood samples through a microfluidic channel coated with type 1 collagen and observe the rate at which platelets adhere to the wall. We compare these results with three-dimensional boundary integral simulations of a suspension of RBCs and platelets in a periodic channel where platelets can adhere to the wall. In both cases, we find that the rate of platelet adhesion varies greatly with the RBC hematocrit. We observe that the relative decrease in platelet activity as hematocrit falls shows a similar profile for simulation and experiment.

Effect of restrictive versus liberal red cell transfusion strategies on haemostasis: systematic review and meta-analysis

Red cells play a key role in normal haemostasis in vitro but their importance clinically is less clear. The objective of this meta-analysis was to assess if correction of anaemia by transfusing red cells at a high haemoglobin threshold (liberal transfusion) is superior to transfusion at a lower haemoglobin threshold (restrictive transfusion) for reducing the risk of bleeding or thrombotic events. We searched for randomised controlled trials in any clinical setting that compared two red cell transfusion thresholds and investigated the risk of bleeding. We searched for studies published up to October 19, 2016 in The Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Embase, and the Transfusion Evidence Library and ISI Web of Science. Relative risks (RR) or Peto Odds Ratios (pOR) were pooled using a random-effect model. Nineteen randomised trials with 9852 participants were eligible for inclusion in this review. Overall there was no difference in the risk of any bleeding between transfusion strategies (RR 0.91, 95 % confidence interval [CI] 0.74 to 1.12). The risk of severe or life-threatening bleeding was lower with a restrictive strategy (RR 0.75, 95 % CI 0.57 to 0.99). There was no difference in the risk of thrombotic events (RR 0.83, 95 % CI 0.61 to 1.13). The risk of any bleeding was not reduced with liberal transfusion and there was no overall difference in the risk of thrombotic events. Data from the included trials do not support aiming for a high haemoglobin threshold to improve haemostasis. PROSPERO registration number CRD42016035519.

Comparison of a restrictive versus liberal red cell transfusion policy for patients with myelodysplasia, aplastic anaemia, and other congenital bone marrow failure disorders

BACKGROUND

Bone marrow failure disorders include a heterogenous group of disorders, of which myelodysplastic syndrome (MDS), forms the largest subgroup. MDS is predominantly a disease of the elderly, with many elderly people managed conservatively with regular allogeneic red blood cell (RBC) transfusions to treat their anaemia. However, RBC transfusions are not without risk. Despite regular transfusions playing a central role in treating such patients, the optimal RBC transfusion strategy (restrictive versus liberal) is currently unclear.

OBJECTIVES

To assess the efficacy and safety of a restrictive versus liberal red blood cell transfusion strategy for patients with myelodysplasia, acquired aplastic anaemia, and other inherited bone marrow failure disorders.

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2015, Issue 4), Ovid MEDLINE (from 1946), Ovid EMBASE (from 1974), EBSCO CINAHL (from 1937), the Transfusion Evidence Library (from 1980) and ongoing trial databases to 26th May 2015.

SELECTION CRITERIA

RCTs including patients with long-term bone marrow failure disorders that require allogeneic blood transfusion, who are not being actively treated with a haematopoietic stem cell transplant, or intensive chemotherapy.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane review methodology. One author initially screened all references, and excluded any that were clearly irrelevant or duplicates. Two authors then independently screened all abstracts of articles, identified by the review search strategy, for relevancy. Two authors independently assessed the full text of all potentially relevant articles for eligibility, completed the data extraction and assessed the studies for risk of bias using The Cochrane Collaboration's 'Risk of bias' tool.

MAIN RESULTS

We included one trial (13 participants) and identified three ongoing trials that assess RBC transfusion strategies in people with MDS.The quality of the evidence was very low across different outcomes according to GRADE methodology.The one included study randomised participants to a restrictive [haemoglobin (Hb) transfusion trigger < 72 g/L, 8 participants] or liberal [Hb trigger < 96 g/L, 5 participants] transfusion policy. There was insufficient evidence to determine a difference in all-cause mortality (1 RCT; 13 participants; RR 0.13, 95% CI 0.01 to 2.32; very low quality evidence). There was insufficient evidence to determine a difference in the number of red blood cell transfusions (1 RCT; 13 participants; 1.8 units per patient per month in the liberal group, compared to 0.8 in the restrictive arm, no standard deviation was reported; very low quality evidence). There were no anaemia-related complications reported (cardiac failure) and no reported effect on activity levels (no statistics provided). The study did not report: mortality due to bleeding/infection/transfusion reactions or iron overload, quality of life, frequency and length of hospital admissions, serious infections (requiring admission to hospital), or serious bleeding (e.g. WHO/CTCAE grade 3 (or equivalent) or above).

AUTHORS' CONCLUSIONS

This review indicates that there is currently a lack of evidence for the recommendation of a particular transfusion strategy for bone marrow failure patients undergoing supportive treatment only. The one RCT included in this review was only published as an abstract and contained only 13 participants. Further randomised trials with robust methodology are required to develop the optimal transfusion strategy for such patients, particularly as the incidence of the main group of bone marrow failure disorders, MDS, rises with an ageing population.

Comparison of a restrictive versus liberal red cell transfusion policy for patients with myelodysplasia, aplastic anaemia, and other congenital bone marrow failure disorders

This is the protocol for a review and there is no abstract. The objectives are as follows: To assess the efficacy and safety of a restrictive versus liberal red cell transfusion strategy for patients with long-term bone marrow failure. These include myelodysplasia, acquired aplastic anaemia, and other inherited bone marrow failure disorders.

Cyclophosphamide intoxication because of pharmacy error in two dogs

CASE DESCRIPTION

An 8-year-old spayed female Yorkshire Terrier and 5-year-old castrated male West Highland White Terrier were evaluated because of cyclophosphamide intoxication subsequent to pharmacy error. Both dogs received cumulative doses of approximately 1,080 mg of cyclophosphamide/m(2) after cyclophosphamide was erroneously dispensed instead of cyclosporine by different pharmacies.

CLINICAL FINDINGS

Both dogs became lethargic, and 1 dog also had anorexia, vomiting, and diarrhea within 2 days after initiation of cyclophosphamide administration. The other dog developed anorexia on the seventh day after initiation of cyclophosphamide administration. The dogs were evaluated by their primary-care veterinarians 9 and 11 days after administration of the first dose of cyclophosphamide, and both had severe leukopenia and thrombocytopenia.

TREATMENT AND OUTCOME

One dog was treated on an outpatient basis with broad-spectrum antimicrobials, granulocyte colony-stimulating factor, and an appetite stimulant. The other dog was more severely affected and was hospitalized for 7 days, during which it was treated with broad-spectrum antimicrobials, gastroprotectants, granulocyte colony-stimulating factor, and cryopreserved platelet and packed RBC transfusions. Both dogs fully recovered after treatment.

CLINICAL RELEVANCE

This was the first report of survival for dogs with inadvertent prolonged cyclophosphamide intoxication subsequent to pharmacy error. Although the 2 dogs had similar clinical signs and clinicopathologic findings, the severity of disease and treatment required differed for each dog. Dogs can recover from prolonged cyclophosphamide intoxication provided appropriate supportive care is administered.

The pathogenesis of traumatic coagulopathy

Over the last 10 years, the management of major haemorrhage in trauma patients has changed radically. This is mainly due to the recognition that many patients who are bleeding when they come in to the emergency department have an established coagulopathy before the haemodilution effects of fluid resuscitation. This has led to the use of new terminology: acute traumatic coagulopathy, acute coagulopathy of trauma shock or trauma-induced coagulopathy. The recognition of acute traumatic coagulopathy is important, because we now understand that its presence is a prognostic indicator, as it is associated with poor clinical outcome. This has driven a change in clinical management, so that the previous approach of maintaining an adequate circulating volume and oxygen carrying capacity before, as a secondary event, dealing with coagulopathy, has changed to haemostatic resuscitation as early as possible. While there is as yet no universally accepted assay or definition, many experts use prolongation of the prothrombin time to indicate that there is, indeed, a coagulopathy. Hypoxia, acidosis and hypothermia and hormonal, immunological and cytokine production, alongside consumption and blood loss, and the dilutional effects of resuscitation may occur to varying extents depending on the type of tissue damaged, the type and extent of injury, predisposing to, or amplifying, activation of coagulation, platelets, fibrinolysis. These are discussed in detail within the article.

Role of transfused red blood cells for shock and coagulopathy within remote damage control resuscitation

The philosophy of damage control resuscitation (DCR) and remote damage control resuscitation (RDCR) can be summarized by stating that the goal is to prevent death from hemorrhagic shock by "staying out of trouble instead of getting out of trouble." In other words, it is preferred to arrest the progression of shock, rather than also having to reverse this condition after significant tissue damage and organ injury cascades are established. Moreover, to prevent death from exsanguination, a balanced approach to the treatment of both shock and coagulopathy is required. This was military doctrine during World War II, but seemed to be forgotten during the last half of the 20th century. Damage control resuscitation and RDCR have revitalized the approach, but there is still more to learn about the most effective and safe resuscitative strategies to simultaneously treat shock and hemorrhage. Current data suggest that our preconceived notions regarding the efficacy of standard issue red blood cells (RBCs) during the hours after transfusion may be false. Standard issue RBCs may not increase oxygen delivery and may in fact decrease it by disturbing control of regional blood flow distribution (impaired nitric oxide processing) and failing to release oxygen, even when perfusing hypoxic tissue (abnormal oxygen affinity). Standard issue RBCs may assist with hemostasis but appear to have competing effects on thrombin generation and platelet function. If standard issue or RBCs of increased storage age are not optimal, then are there alternatives that will allow for an efficacious and safe treatment of shock while also supporting hemostasis? Studies are required to determine if fresh RBCs less than 7 to 10 days provide an outcome advantage. A resurgence in the study of whole blood stored at 4°C for up to 10 days also holds promise. Two randomized controlled trials in humans have indicated that following transfusion with either whole blood stored at 4°C or platelets stored at 4°C there was less clinical bleeding than when blood was reconstituted with components or when platelets were stored at 22°C. Early reversal of shock is essential to prevent exacerbation of coagulopathy and progression of cell death cascades in patients with severe traumatic injuries. Red blood cell storage solutions have evolved to accommodate the needs of non-critically ill patients yet may not be optimal for patients in hemorrhagic shock. Continued focus on the recognition and treatment of shock is essential for continued improvement in outcomes for patients who require damage control resuscitation and RDCR.

Intracranial haemorrhage in thrombocytopenic haematology patients--a nested case-control study: the InCiTe study protocol

INTRODUCTION

Intracranial haemorrhage (ICH) is one of the most serious side-effects of severe thrombocytopenia in haematology patients. ICH is rare, but can have devastating consequences (death or major morbidity). It is unknown why some patients with severe thrombocytopenia bleed and others do not.

STUDY AIMS

Primary aim was to identify risk factors for ICH in patients with haematological malignancies. Secondary aims were to identify short-term outcomes for these patients at 30 days (major morbidity and mortality) and produce a more accurate estimate of ICH incidence in this population. This information is key to identifying means to improve treatment and quality of care.

METHODS/ANALYSIS

This is a UK-wide case-control study of ICH nested within a 4-year prospective surveillance study set up specifically for the case-control study. Each case will be matched to one control. Cases will be adult haematology patients (≥16 years) who have had any type or severity of ICH who are receiving, about to receive or have just received myeloablative chemotherapy (defined as chemotherapy expected to cause a significant thrombocytopenia <50×10(9)/L for >5 days) or a haemopoietic stem cell transplant. Only patients being treated with curative intent will be included. Controls will be patients who fulfil the same inclusion criteria as cases (apart from ICH) and were treated at the same hospital immediately before the index case. Cases and controls will be matched to type of treatment (myeloablative chemotherapy or haemopoietic stem cell transplant). Hospitals across the UK will participate in a monthly email reporting strategy (started June 2011), as to whether a case of ICH occurred during the preceding calendar month. Case and control forms will be sent to any hospital reporting an eligible case. Conditional logistic regression will be used to calculate ORs. Denominator data for incidence estimates will use national registry data.

STUDY REGISTRATION

ISRCTN05026912 (prospective registration). NIHR Portfolio (UKCRN ID 10712).

Pathology consultation on monitoring direct thrombin inhibitors and overcoming their effects in bleeding patients

OBJECTIVES

Direct thrombin inhibitors (DTIs), a relatively new class of anticoagulants, present several challenges regarding monitoring of their anticoagulant effects and overcoming bleeding associated with their use. The aim of this article is to (1) briefly present the pharmacologic properties of currently available DTIs, (2) discuss approaches to laboratory assessment of these drugs, and (3) review management of bleeding associated with their use.

METHODS

Published literature on DTIs, including clinical trials, case reports, and experimental animal models, was reviewed. The primary authors also reviewed their first-hand experiences with DTI anticoagulation.

RESULTS

Based on the literature review and the practical experiences of the authors, suggestions for the monitoring of DTIs and algorithmic approaches for the management of DTI-associated bleeding were developed.

CONCLUSIONS

Routine coagulation assays (eg, the prothrombin time) show a relatively poor correlation with the degree of anticoagulation and DTI drug concentrations. Newer assays, such as the ecarin clotting time and dilute thrombin time, may be more useful in assessing DTI anticoagulation, but these assays are not yet widely available. Low-grade DTI-associated bleeds are best managed with cessation of the drug and supportive care, while higher-grade and/or life-threatening bleeds may best be reversed by active drug removal (eg, via the administration of activated charcoal or hemodialysis). At present there is little evidence to suggest that transfusion products such as factor concentrates or thawed plasma are of any particular benefit in DTI reversal; however, these products may play a supportive role in the management of bleeding.

Transfusion medicine in small animals

This article reviews the use of transfusion medicine in veterinary medicine and discusses current research regarding donor screening and component therapy. Typing and crossmatching methodologies are discussed. Available components, potential uses, and controversies in treatment are also discussed.

Pre-liver transplant protocols in dentistry

The number of adults with end stage liver disease in the U.S., awaiting liver transplantation, has maintained a steady upward trend in recent years. Concurrently, the survival rate of liver transplant recipients has also been on the rise. To be able to safely treat this population, dentists should have familiarity with special management requirements of patients with end stage liver disease. This article reviews the historical background on liver transplantation and provides updated information on indications and evaluation protocols, treatment considerations in end stage liver disease, clinical dental management protocols prior to surgical procedures and dental considerations in the pre-liver transplant candidates.

Anaemia on Admission is Associated with More Severe Intracerebral Haemorrhage and Worse Outcomes

Background

Lower haemoglobin levels may impair cerebral oxygen delivery and threaten tissue viability in the setting of acute brain injury. Few studies have examined the association between haemoglobin levels and outcomes after spontaneous intracerebral haemorrhage.

Aims

We evaluated whether anaemia on admission was associated with greater intracerebral haemorrhage severity and worse outcome.

Methods

Consecutive patients with spontaneous intracerebral haemorrhage were analyzed from the Registry of the Canadian Stroke Network. Admission haemoglobin was related to stroke severity (using the Canadian Neurological Scale), modified Rankin score at discharge, and one-year mortality. Adjustment was made for potential confounders including age, gender, medical history, warfarin use, glucose, creatinine, blood pressure, and intraventricular haemorrhage.

Results

Two thousand four hundred six patients with intracerebral haemorrhage were studied of whom 23% had anaemia (haemoglobin <120 g/l) on admission, including 4% with haemoglobin <100 g/l. Patients with anaemia were more likely to have severe neurological deficits at presentation [haemoglobin ≤100 g/l, adjusted odds ratio 4·04 (95% confidence interval 2·39, 6·84); haemoglobin 101–120 g/l, adjusted odds ratio 1·93 (95% confidence interval 1·43, 2·59), both P < 0·0001]. In nonanticoagulated patients, severe anaemia was also associated with poor outcome (modified Rankin score 4–6) at discharge [haemoglobin ≤100 g/l, adjusted odds ratio 2·42 (95% confidence interval 1·07–5·47), P= 0·034] and increased mortality at one-year [haemoglobin ≤100 g/l, adjusted hazard ratio 1·73 (95% confidence interval 1·22–2·45), P = 0·002].

Conclusions

Anaemia on admission is associated with greater intracerebral haemorrhage severity and worse outcomes. The utility of transfusion remains unclear in this setting.

Use of fresh platelet concentrate or lyophilized platelets in thrombocytopenic dogs with clinical signs of hemorrhage: a preliminary trial in 37 dogs

OBJECTIVE

To examine the safety and feasibility of using lyophilized platelets (LYO) and fresh platelet concentrate (FRESH) in bleeding thrombocytopenic dogs.

DESIGN

Preliminary prospective randomized clinical trial.

SETTING

Two private referral centers and 3 university teaching hospitals.

ANIMALS

Thirty-seven dogs with a complaint of hemorrhage associated with thrombocytopenia (platelet count <70 × 10(9) /L [70,000/μL], a hematocrit >15%, and that had received neither vincristine nor platelet-containing transfusions within 72 h of enrollment were studied.

INTERVENTIONS

Animals were randomized to receive LYO or FRESH, dosed according to weight. Physical examination, complete blood counts, and coagulation testing (prothrombin time and activated partial thromboplastin time) were performed at enrollment. Physical examinations were also performed immediately post transfusion, and at 1 and 24 h after transfusion. Complete blood counts were repeated immediately post transfusion and at 24 h. Collected data included bleeding score (BLS), response to transfusion, adverse reactions, hospitalization time, need for additional transfusions, survival to discharge, and 28-d survival.

MEASUREMENTS AND MAIN RESULTS

Twenty-two dogs received LYO and 15 received FRESH. There was no difference between groups in age, weight, BLS, platelet count, white blood cell count, hematocrit, or presence of melena. There was no difference between groups in transfusion reaction rates, the need for additional transfusions, 24-h BLS, hospitalization time, survival to discharge, or 28-d survival.

CONCLUSIONS

Transfusion of LYO was feasible and associated with a low transfusion reaction rate in this limited study of thrombocytopenic canine patients presenting with mild-to-severe hemorrhage. LYO were easy to use and provided storage advantages over FRESH. Further study of this product, including examination of efficacy and platelet life span, is warranted.

Red blood cells mediate the onset of thrombosis in the ferric chloride murine model

Application of ferric chloride (FeCl(3)) to exposed blood vessels is widely used to initiate thrombosis in laboratory mice. Because the mechanisms by which FeCl(3) induces endothelial injury and subsequent thrombus formation are little understood, we used scanning electron and brightfield intravital microscopy to visualize endothelial damage and thrombus formation occurring in situ. Contrary to generally accepted belief, FeCl(3) does not result in appreciable subendothelial exposure within the time frame of thrombosis. Furthermore, the first cells to adhere to FeCl(3)-treated endothelial surfaces are red blood cells (RBCs) rather than platelets. Energy dispersive x-ray spectroscopy demonstrated that ferric ions predominantly localize to endothelial-associated RBCs and RBC-derived structures rather than to the endothelium. With continuing time points, RBC-derived structures rapidly recruit platelets, resulting in large complexes that subsequently enlarge and coalesce, quickly covering the endothelial surface. Further studies demonstrated that neither von Willebrand factor nor platelet glycoprotein Ib-α receptor (GPIb-α) is required for RBCs to adhere to the endothelium, and that deficiency of GPIb-α greatly abrogated the recruitment of platelets to the endothelial-associated RBC material. These findings illuminate the mechanisms of FeCl(3)-mediated thrombosis and reveal a previously unrecognized ability of RBCs to participate in thrombosis by mediating platelet adhesion to the intact endothelial surface.

Frozen blood products: clinically effective and potentially ideal for remote Australia

The development of effective cryopreservation techniques for both red blood cells and platelets, which maintain ex vivo biological activity, in combination with frozen plasma, provides for a unique blood banking strategy. This technology greatly enhances the storage life of these products. The rationale and potential advantages of using cryopreservation techniques for the provision of blood products to remote and military environments have been effectively demonstrated in several conflicts over the last decade. Current haemostatic resuscitation doctrine for the exsanguinating patient supports the use of red blood cells, platelets and frozen plasma early in the resuscitation. We believe an integrated fresh-frozen blood bank inventory could facilitate provision of blood products, not only in the military setting but also in regional Australia, by overcoming many logistic and geographical challenges. The processes involved in production and point of care thawing are sufficiently well developed and achievable to make this technology a viable option. The potential limitations of cryopreservation and subsequent product thawing need to be considered if such a strategy is to be developed. A substantial body of international experience using cryopreserved products in remote settings has already been accrued. This experience provides a template for the possible creation of an Australian integrated fresh-frozen blood bank inventory that could conceivably enhance the care of patients in both regional Australia and in the military setting.

Postoperative bleeding after dental extraction in liver pretransplant patients

PURPOSE

The aim of this prospective observational study was to evaluate the incidence of postoperative bleeding after dental extraction in candidates for liver transplantation and the efficacy of the association of tranexamic acid and absorbable hemostatic sponges.

PATIENTS AND METHODS

All individuals referred for oral health evaluation requiring extraction were considered in this study. Patients were included in the analysis when the blood examinations showed a platelet count of 30,000/mm(3) or greater and an international normalized ratio (INR) of 3.0 or less. In group 1 local pressure was applied by use of gauze soaked with tranexamic acid, and in group 2 gauze without tranexamic acid was used. Absorbable hemostatic sponges and cross sutures were used as a standard hemostatic measure.

RESULTS

In the 23 patients included in this study, 84 simple extractions were performed during 35 dental surgical procedures. The main preoperative blood tests found the following: a mean hematocrit level of 34.54% (SD, 5.84%; range, 21.7%-44.4%), platelet counts from 31,000/mm(3) to 160,000/mm(3), and a mean INR of 1.50 (SD, 0.39; range, 0.98-2.59). Postoperative bleeding occurred during only 1 procedure (2.9%), and local pressure with gauze was effective for achieving hemostasis. No statistically significant difference in the time to hemostasis was found between the 2 groups.

CONCLUSIONS

This study found a low risk of bleeding for tooth extractions in patients with liver cirrhosis, INRs of 2.50 or less, and platelet counts of 30,000/mm(3) or greater. Blood transfusions were not needed, and in the case of postoperative bleeding, the use of local hemostatic measures was satisfactory.

Outcomes following early red blood cell transfusion in acute upper gastrointestinal bleeding

BACKGROUND

Acute upper gastrointestinal bleeding (AUGIB) accounts for 14% of RBC units transfused in the UK. In exsanguinating AUGIB the value of RBC transfusion is self evident, but in less severe bleeding its value is less obvious.

AIM

To examine the relationship between early RBC transfusion, re-bleeding and mortality following AUGIB, which is one of the most common indications for red blood cell (RBC) transfusion.

METHOD

Data were collected on 4441 AUGIB patients presenting to UK hospitals. The relationship between early RBC transfusion, re-bleeding and death was examined using logistic regression.

RESULTS

44% were transfused RBCs within 12 hours of admission. In patients transfused with an initial haemoglobin of <8 g/dl, re-bleeding occurred in 23% and mortality was 13% compared with a re-bleeding rate of 15%, and mortality of 13% in those not transfused. In patients transfused with haemoglobin >8 g/dl, re-bleeding occurred in 24% and mortality was 11% compared with a re-bleeding rate of 6.7%, and mortality of 4.3% in those not transfused. After adjusting for Rockall score and initial haemoglobin, early transfusion was associated with a two-fold increased risk of re-bleeding (Odds ratio 2.26, 95% CI 1.76-2.90) and a 28% increase in mortality (Odds ratio 1.28, 95% CI 0.94-1.74).

CONCLUSIONS

Early RBC transfusion in AUGIB was associated with a two-fold increased risk of re-bleeding and an increase in mortality, although the latter was not statistically significant. Although these findings could be due to residual confounding, they indicate that a randomized comparison of restrictive and liberal transfusion policies in AUGIB is urgently required.

Differential effect of materials for surface hemostasis on red blood cell morphology

The design of devices for surface (topical) hemostasis has been based on maximizing activation of platelets and accelerating coagulation pathways. The studies reported herein examine another aspect of blood contact with topical hemostasis materials, i.e., surface binding of red blood cells (RBCs) and related alterations in RBC morphology. Whole blood was allowed to contact poly-N-acetyl glucosamine (pGlcNAc) containing materials: pGlcNAc nanofibers with parallel polymer alignment (beta-pGlcNAc), chitin, and chitosan. The effect on RBC morphology and function via contact with the artificial surfaces on the cell's morphology was examined with scanning and transmission electron microscopy (TEM). beta-pGlcNAc was found to densely bind RBCs and induce a stomatocytic-like morphology. Chitin and chitosan also bound RBCs, but with approximately 10-fold lower levels and with less distinct general morphologies. beta-pGlcNAc is thus unique in the nature of its interaction with RBCs. These studies indicate that the differential ability of various materials to bind and alter the morphology of RBCs at the artificial surface interface with blood is an important consideration in the design of devices for surface hemostasis.

The effects of nonsteroidal anti-inflammatory drugs on platelet function and severity of upper gastrointestinal haemorrhage

Nonsteroidal anti-inflammatory drugs (NSAIDs) cause gastrointestinal (GI) damage primarily due to the inhibition of prostaglandin synthesis in gastric mucosa, which is an important factor in mucosa protection. Platelets are a cardinal feature of vascular repair. A variety of angiogenic stimulators are stored in platelets and are released during clotting at the wound. When there is a defect in any of these functions and/or platelet number, haemostasis is usually impaired and there may be an associated increased risk and severity of bleeding. While the mechanism of mucosal injury and bleeding are well documented with the use of NSAIDs, very little is known about the platelet function abnormalities and their effects on severity of upper GI bleedings. We performed a prospective analysis of 49 patients who had a history of NSAIDs use to investigate the association between the platelet function impairment associated with NSAIDs and severity of upper GI haemorrhages. Thirty-six of 49 patients (73.5%) had deteriorated platelet function. Mean severity score of patients with deteriorated platelet functions was 3.39, and that of patients with normal platelet functions was 2.46. Mean severity score was statistically significantly higher in patients with deteriorated platelet functions. In conclusion, impaired platelet functions associated with NSAIDs may cause more severe upper GI bleeding. Clinicians should be alert for GI complications especially in older patients and in those with a history of ulcer bleeding.